I've never ridden it, but--taking Rt 20 north to Orange, and then 15 north to Culpeper, would at least avoid some of the worst of 29, and only leave you with a bit of 29 before 28. Not that 28 is ideal on a busy day, but I guess you don't want to end up on I-66 on a 250....

Or, if you have time, from Orange instead of 15 you could take 615 (Rapidan Road) to 522 north to 3 west to 29 in Culpeper. 615 is a nice route, but I don't know about 522.